Add ActiveMQ MQTT connection URL auto-detection

Fixes gh-1638

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jms/activemq/ActiveMQConnectionFactoryFactory.java

@@ -16,8 +16,13 @@
 
 package org.springframework.boot.autoconfigure.jms.activemq;
 
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
 import org.apache.activemq.ActiveMQConnectionFactory;
 import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -33,6 +38,14 @@ class ActiveMQConnectionFactoryFactory {
 
 	private static final String DEFAULT_NETWORK_BROKER_URL = "tcp://localhost:61616";
 
+	private static final Map<String, String> CLASS_BASED_BROKER_URLS;
+	static {
+		Map<String, String> map = new LinkedHashMap<String, String>();
+		map.put("org.apache.activemq.transport.mqtt.MQTTTransport",
+				"mqtt://localhost:1883");
+		CLASS_BASED_BROKER_URLS = Collections.unmodifiableMap(map);
+	}
+
 	private final ActiveMQProperties properties;
 
 	public ActiveMQConnectionFactoryFactory(ActiveMQProperties properties) {
@@ -67,6 +80,13 @@ class ActiveMQConnectionFactoryFactory {
 		if (this.properties.getBrokerUrl() != null) {
 			return this.properties.getBrokerUrl();
 		}
+		if (this.properties.isAutodetectConnectionUrl()) {
+			for (Map.Entry<String, String> entry : CLASS_BASED_BROKER_URLS.entrySet()) {
+				if (ClassUtils.isPresent(entry.getKey(), null)) {
+					return entry.getValue();
+				}
+			}
+		}
 		if (this.properties.isInMemory()) {
 			return DEFAULT_EMBEDDED_BROKER_URL;
 		}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jms/activemq/ActiveMQProperties.java

@@ -29,6 +29,8 @@ public class ActiveMQProperties {
 
 	private String brokerUrl;
 
+	private boolean autodetectConnectionUrl = true;
+
 	private boolean inMemory = true;
 
 	private boolean pooled;
@@ -45,6 +47,14 @@ public class ActiveMQProperties {
 		this.brokerUrl = brokerUrl;
 	}
 
+	public boolean isAutodetectConnectionUrl() {
+		return this.autodetectConnectionUrl;
+	}
+
+	public void setAutodetectConnectionUrl(boolean autodetectConnectionUrl) {
+		this.autodetectConnectionUrl = autodetectConnectionUrl;
+	}
+
 	/**
 	 * Specify if the default broker url should be in memory. Ignored if an explicit
 	 * broker has been specified.

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -284,6 +284,7 @@ content into your application; rather pick only the properties that you need.
 	spring.activemq.broker-url=tcp://localhost:61616 # connection URL
 	spring.activemq.user=
 	spring.activemq.password=
+	spring.activemq.autodetect-connection-url=true # attempt to guess URL based on classpath
 	spring.activemq.in-memory=true # broker kind to create if no broker-url is specified
 	spring.activemq.pooled=false